98 Annals Entomological Society of America [Vol. III. 



All the parts of the labium and maxillae are described as if 

 looking at the exposed surface from below or from behind accord- 

 ing to the position in which the caterpillar holds its head. This 

 surface morphologically consists of the caudal aspect of the 

 labium, and the caudo-lateral aspect of the maxillae. 



The maxillae are fused at the base with the labium, but are 

 free at the tip. The main part is made up of a usually lightly 

 chitinized joint, the stipes (plus the palpifer) which bears two 

 setae at its distal end. The cardo forms a small triangle between 

 the base of the stipes and the submentum. At the tip of the 

 stipes there are two very incomplete rings, which would seem 

 to be the basal joints of the palpus, but which are completely 

 fused with the maxilla proper. In Hepialus the more distal of 

 these is shaped like a normal joint of the palpus, and in Microp- 

 teryx, according to Packard, it is free. From the end of these 

 arises the two-jointed free part of the palpus, and mesad of this 

 sjmngs the large basal joint of the galea, which forms an incom- 

 })lete ring. The tip of this joint bears the two maxillary lobes 

 (which are the distal joints of the galea and lacinia?), and is 

 also armed with two large cones (anterior to the maxillary lobes 

 in Frenatae, and mesad to them in Hepialus), two small cones 

 (posterior to the maxillary lobes) and a step-cone between them. 

 The latter is composed of a larger chitinous ring, bearing a thin- 

 walled cone at its tip. Each of the maxillary lobes, also, bears 

 a sense-cone at its tip. 



Chitinous sclerites are but little developed as a rule on the 

 body. The greatest development that I have seen on the abdo- 

 men occurs in Incurvaria. In this caterpillar each segment has 

 two dorsal and two ventral plates (see Fig. 34). The anterior 

 ventral plate, or sternum, extends between the prolegs. 



The thorax has more extensive sclerites in Adela, as the 

 sketch of the pro- and meso-thorax (Fig. 35) shows. Not many 

 of the sutures are traceable, so that they can be only roughly 

 homologized with those of other insects. The prscsternum and 

 sternellum of the prothorax are more distinct. 



In higher caterpillars only the coxaj, which are divided by a 

 clear suture into coxa and meron, are preserved. Besides the 

 coxa^, the legs have very short femurs and tibiae and a single- 

 jointed tarsus, which bears one claw. 



One of the chief characteristics of the caterpillars is the 

 definite arrangement of setae. These are either primary, which 



